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A Two-Scale Computational Model of pH-Sensitive Expansive Porous Media
Ranena V Ponce F1, Márcio A Murad2, Sidarta A Lima3
1Pontifícia Universidade Católica do Rio de Janeiro PUC/RJ , Department of Mechanical Engineering, R. Marques de Sao Vicente 225 , Gavea, 22453-900 , Rio de Janeiro, RJ , Brazil
Journal of Applied Mechanics
|June 4, 2014
Summary
This study introduces a novel two-scale model to predict swelling pressure in colloidal systems, accounting for pH-dependent microstructure changes. The model accurately simulates swelling behavior induced by chemical stimuli.
Area of Science:
- Colloid and Surface Science
- Computational Mechanics
- Materials Science
Background:
- Colloidal systems exhibit microstructure sensitive to pH changes.
- Understanding swelling pressure is crucial for predicting material behavior.
Purpose of the Study:
- To develop and validate a new two-scale model for computing swelling pressure in pH-sensitive colloidal systems.
- To incorporate pH-dependent surface charge density and its effect on swelling.
Main Methods:
- Pore-scale modeling of a biphasic porous medium with charged macromolecules and electrolyte solution.
- Homogenization using matched asymptotic expansions to derive macroscale equations.
- Finite element method for numerical simulation of free swelling experiments.
Main Results:
- Rigorous derivation of modified Terzaghi's effective stress principle and solid phase mass balance.
- Inclusion of a disjoining stress tensor and electrochemical compressibility in constitutive laws.
- Development of pH-dependent constitutive laws for swelling pressure.
Conclusions:
- The proposed two-scale model accurately captures swelling pressure in pH-sensitive colloidal systems.
- The model provides a robust framework for simulating chemically induced swelling.
- This work advances the understanding of microstructure evolution in response to environmental changes.
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